2 7 Ju l 2 00 9 The Galaxy Population of Low - Redshift Abell Clusters

We present a study of the luminosity and color properties of galaxies selected from a sample of 57 low-redshift Abell clusters. We utilize the non-parametric dwarf-to-giant ratio (DGR) and the blue galaxy fraction (fb) to investigate the clustercentric radial-dependent changes in the cluster galaxy population. Composite cluster samples are combined by scaling the counting radius by r200 to minimize radius selection bias. The separation of galaxies into a red and blue population was achieved by selecting galaxies relative to the cluster color-magnitude relation. The DGR of the red and blue galaxies is found to be independent of cluster richness (Bgc), although the DGR is larger for the blue population at all measured radii. A decrease in the DGR for the red and red+blue galaxies is detected in the cluster core region, while the blue galaxy DGR is nearly independent of radius. The fb is found not to correlate with Bgc; however, a steady decline toward the inner-cluster region is observed for the giant galaxies. The dwarf galaxy fb is approximately constant with clustercentric radius except for the inner cluster core region where fb decreases. The clustercentric radial dependence of the DGR and the galaxy blue fraction, indicates that it is unlikely that a simple scenario based on either pure disruption or pure fading/reddening can describe the evolution of infalling dwarf galaxies; both outcomes are produced by the cluster environment. Subject headings: galaxies: clusters: general — galaxies: luminosities: colors — galaxies: dwarf — galaxies: formation — galaxies: evolution Department of Physics and Astrophysics, University of North Dakota, Grand Forks, ND 58202; email: [email protected] Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON, Canada, M5S 3H8; email: [email protected] Instituto Nacional de Astrof́ısica, Optica y Electrónica, Tonantzintla, Pue., México; email: [email protected] Visiting Astronomer, Kitt Peak National Observatory. KPNO is operated by AURA, Inc. under contract to the National Science Foundation.